---
id: EXPO-15
family: GR-EXPO
level: extended
profiles: [storage-api, runtime]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/gr-expo/expo-15
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# EXPO-15 — A model may fill only visible, unwired parameters

*GR-EXPO (Part I) · level: extended · profiles: storage-api, runtime · added in 1.0*

## The rule

> **Normative.** This is the rule.
>
> 1. Where a node is offered to an agent node as a callable tool, a parameter is fillable by the model when it is connectable and exposed and no data edge already feeds that port.
>
> 2. A hidden parameter, a non-connectable one, and one a wire already supplies are all outside the model's reach.


## What it means

A parameter reaches the model only when three things hold at once:
connectable, exposed, and not already fed by a wire. Missing any one pins
it — the model cannot fill it, and it does not even appear in the schema
offered to the model. The wire check is independent of the other two: a
wired parameter is withheld because a wire's value is deterministic run
state, and the model must not compete with it, whether or not that same
parameter would otherwise be exposed. A parameter the workflow hides is
withheld the same way, whether the hiding comes from an explicit instance
override or from the node type's own default exposure.

## Example

A node offers four parameters as a callable tool: two connectable and
exposed by default, one not connectable, and one internal.

```json title="The parameters the model may fill, nothing wired" verdict="fillable"
["query", "url"]
```

```json title="The same parameters, with url fed by a data edge" verdict="fillable"
["query"]
```

The non-connectable and internal parameters never appear in either list —
being wired or hidden was never the reason they were excluded.

## Related rules

- Names: EXPO-2, EXPO-10

---

Rule identifiers are permanent and are never renumbered. This specification carries
no implementation status: each implementation publishes its own standing against
these rules. Licensed CC BY 4.0.